Transition from zexe_algebra/snarkos_toolkit to snarkVM

[apruden2008]

Currently, much of the aleo-setup repository depends on zexe-algebra. This dependency is either direct, or indirect through another library in snarkOS. However, we've implemented all of the required logic in our own repo (snarkVM), and therefore snarkos_toolkit is being deprecated. In order to ensure consistency and minimize external dependencies, we should migrate all of our code over to depend on snarkVM

[ibaryshnikov]

Done in #317